Currently, more and more terminal devices have a touchscreen. An active stylus 101 may be used to write or input an instruction to a terminal device 104 having a touchscreen, such as a computer with a screen, a mobile terminal device, a graphic tablet and the like, so as to implement human-computer interaction, as shown in FIG. 1.
The active stylus 101 outputs an encoded signal via a stylus tip 103 at an end of a stylus head 102, so as to implement communication between the active stylus 101 and the terminal device 104 having the touchscreen. The encoded signal output by the stylus tip 103 is usually a high-voltage signal, so as to increase a signal-to-noise ratio of a communication signal between the active stylus 101 and the terminal device 104 having the touchscreen.
During implementing the present disclosure, it is found that the existing technologies at least have the following problems: a current solution of implementing high-voltage encoding by the stylus tip 103 is mainly an LC resonance encoding. In an LC resonance circuit, an inductor and a capacitor form a series resonance circuit. A power source in the active stylus 101 provides an energy input to the LC resonance circuit. The LC resonance circuit outputs a high-voltage encoded signal to the stylus tip 103. However, in the LC resonance circuit, once the inductor and the capacitor are chosen, a frequency of an output high voltage of the circuit is fixed and non-adjustable, resulting in that a signal-to-noise ratio of the LC resonance circuit is fixed and cannot be increased. Moreover, an amplitude of the output high voltage of the LC resonance circuit is also fixed and non-adjustable, resulting in that system power consumption cannot be reduced.